In recent years, the grocery industry has extensively adopted the use of wooden pallets for storing and handling of goods. The palletized goods are normally stored in warehouses or centralized distribution centers, from which the goods are then distributed to numerous retail outlets. By maintaining the goods on the pallets, the goods can thus be stacked on the pallets at the manufacturer and shipped to the centralized distribution center, with the goods then being maintained and stored on these pallets. Following unloading, the pallets are recycled for further use. This system greatly simplifies the handling, storing and shipment of the goods. To further simplify the handling within the warehouse or distribution center, and to permit proper rotation of goods, these centralized warehouses have also adopted rack-type storage systems employing conveyors which permit the goods to be stored and handled on a "first in-first out" basis.
One of the problems experienced with the use of palletized loads, and their handling and storing on roller-type conveyors, is that of pallet deterioration and the resulting damage to the conveyor rollers. As the wood pallets are used, which involves the depositing thereon of rather heavy loads and the movement thereof by forklifts and other devices, the nails in the pallet tend to loosen which results in the nail heads being slightly exposed. This is particularly critical with respect to the nails which secure the bottom deckboards to the intermediate stringers. When these pallets, particularly with a heavy load thereon, are deposited on a roller conveyor, the stringers are normally positioned directly over the rollers so as to permit proper transfer of load from the pallet to the conveyor. If the bottom nail heads protrude slightly from the bottom deckboards, then the nail heads directly contact the rollers and cause gouging thereof. The surfaces of the rollers thus become damaged sufficiently to prevent efficient free movement of the pallets thereover, such that replacement of the rollers is necessary.
This problem of the nails continually loosening during handling of the loaded pallets also requires that the pallets be reconditioned in order to permit their continued use. This reconditioning normally involves manual inspection of the pallets, and a hammering of the nails back into the stringers. This is obviously a manual operation which is both time consuming and costly.
Accordingly, the present invention relates to an improved conveyor-type storage method for palletized loads employing wood pallets so as to overcome or at least minimize the above problems by permitting the nails associated with the lower deckboards to be continuously impacted against braking flanges associated with the conveyor to thereby prevent loosening of the nails.
In the method of this invention, the palletized loads are deposited on a gravity-type conveyor at the upper end thereof, and are moved by gravity toward the lower end, with the palletized loads being stored on the conveyor until the load at the lower end is removed, whereupon the loads are then automatically advanced downwardly. The conveyor includes a pair of substantially parallel roller assemblies which vertically cyclically reciprocate up and down according to a preselected pattern, the reciprocation of the roller assemblies being controlled by pneumatically inflatable hoses positioned below the roller assemblies. Upon inflation, the roller assemblies are lifted upwardly to permit gravity-urged advance of the palletized loads, and upon deflation the loads are automatically lowered into braking engagement with stationary brake flanges positioned adjacent the roller assemblies. The wood pallets are positioned so that the outermost stringers are not disposed directly over the rollers, but rather are positioned directly over the braking flanges so that the repetitive lowering and hence impacting of the pallets on the braking flanges causes the nails associated with the lower transversely-extending deckboards to be continually pounded into the stringers. In this manner, not only are the nails in the lower deckboards positioned so that they do not contact and damage the rollers, but they are also continuously subjected to impact forces so that the nails have little opportunity to significantly loosen.